1. Field of the Invention
The present invention relates generally to the field of the mechanical design of the chassis for electric vehicles and specifically electric passenger cars and in particular to the design of battery enclosures, battery pack enclosure mounting frame and electric motor mounting frame.
2. Description of the Related Art
There are two main approaches to implementing an electric vehicle or EV (a vehicle that uses an electric motor as its main propulsion unit and is powered by an electric battery). The first approach is to design and build an electric vehicle from the ground up. While allowing for the maximum flexibility in design choices, this approach is very expensive, time consuming and complex—both from a systems design perspective, as well as from a regulatory compliance perspective. The second, more cost-effective, approach is to use an existing gasoline vehicle chassis as a mechanical platform for designing and building an electric vehicle. When applied to the existing internal combustion engine (ICE) vehicle, this methodology is referred to as an “electric conversion”. The aforesaid conversion process may also be applied to a bare ICE vehicle chassis (a “glider” vehicle). The various described inventive systems and processes provide a cost-effective, highly manufacturable implementation of the aforesaid second approach for implementing an EV. The following description will concentrate on applying the various embodiments of the inventive systems and processes to an existing ICE vehicle platform. However, as it would be appreciated by those of skill in the art, the same inventive methodology as described hereinbelow can be applied to the aforesaid “glider” vehicle as well. Furthermore, it should be emphasized at the outset, that the inventive methodologies and systems described herein are not limited to conversions of electrical passenger cars only, but could be adopted, with or without modifications or alterations, for use in any other suitable vehicle.
As would be appreciated by those of skill in the art, in the process of converting an ICE car into the 100% electric vehicle the majority of mechanical components of the ICE car can be left intact. Parts that are removed from the ICE vehicle may include: the internal combustion engine (with certain attached accessory components such as power steering pump, vacuum pump, alternator etc.), the exhaust system, the fuel tank, the radiator and the 12V lead-acid battery. The new parts that are installed in the converted vehicle may include: the electric motor with the motor mount, the battery pack composed of several battery enclosures holding and securing multiple battery cells and the frame supporting those enclosures.
Various mechanical parts, systems and assemblies in a modern passenger vehicle have to meet a large set of requirements related to durability, resistance to vibration, resistance to corrosion and the like. Because of the considerable weight of the batteries in an electric vehicle, battery enclosure housing such batteries must be designed to be strong enough to carry a large weight (˜700 lb in one exemplary converted car) and has to routinely withstand significant acceleration forces in every direction, reaching 1 g in normal operating conditions, which results in high levels of mechanical stress exerted on the enclosure structure and mounts. At the same time, the aforesaid battery enclosure must be waterproof, and should be able to withstand corrosion and vibration.
The same mechanical design requirements that apply to the structure of the enclosure itself, also apply to the enclosure mounting elements, which may include a vehicle frame or a dedicated sub-frame. In addition, such goals as weight reduction and the ability to crumble during the crash impact should also be considered in designing the battery enclosure mount.
Furthermore, the electric motor mounts should be able to bear the weight of the motor, withstand substantial acceleration force in any direction and also withstand the full torque produced by the electric motor. Due to the inherent nature of the electric motors, the torque application can be very sudden and can generate much larger stresses on the mechanical mounting system compared to the gasoline engine rated at the same torque/power output.
Most of the existing electric car conversions are highly customized, hand crafted. Parts for such conversions are not designed with industrial production scalability in mind. The process itself is highly complicated requiring significant knowledge and experience in mechanics, electrical engineering in general and specifically in power electronics. Hence those conversions are not generally suitable for production on an industrial scale.